Deep into that Darkness Peering . . . Stood There Wondering, Fearing

This chapter reviews the diagnosis and management of irregular sleep/wake rhythm disorder (ISWRD) and sundowning. ISWRD is characterized by lack of a clearly defined sleep/wake circadian rhythm with episodes of sleep and wake at varying times of the day or night, unrelated to a normal sleep/wake, day/night circadian rhythm Patients with neurodegenerative disorders are at increased risk for ISWRD. The diagnosis of ISWRD requires sleep log or actigraphy monitoring for at least 7 days. ISWRD is a common cause of institutionalization. Sundowning can further disrupt sleep and has been associated with more rapid progression of dementia. Mixed-modality treatment is used for the treatment of ISWRD and involves the integration of approaches to optimize entrainment to synchronizing factors and behavioral therapy.